1. Field of the Invention
The present invention relates generally to methods of rapidly consolidating particulate materials in wells such as incompetent formation sands, proppant materials and gravel packing materials.
2. Description of the Prior Art
Oil and gas wells are often completed in subterranean producing zones containing loose and incompetent sands. Heretofore, such loose and incompetent sands have been consolidated into stationary permeable masses by injecting a hardenable resin composition into the producing zones. That is, the incompetent sands in the producing zones are coated with the hardenable resin composition and then the resin composition is caused to harden whereby the sands are consolidated into permeable masses.
The producing zones in oil and gas wells are also often stimulated by hydraulic fracturing. In a hydraulic fracturing procedure, a gelled fracturing fluid is pumped into the zone to be fractured at a rate and pressure such that one or more fractures are formed and extended in the zone. A solid particulate proppant material, e.g., sand, for propping the fractures open is suspended in a portion of the fracturing fluid so that the proppant material is deposited in the fractures. In some instances, all or a part of the proppant material has heretofore been coated with a hardenable resin composition. The resin composition has been caused to harden after the proppant material has been placed in the fractures so that the proppant material is consolidated into a stationary permeable mass. Such consolidation prevents proppant flow-back with fluids produced from the fractured formation.
In gravel packing operations, solid gravel particles such as sand are carried to a subterranean zone or formation in which a gravel pack is to be placed in a gelled carrier fluid. The gravel pack is typically formed between a screen and the walls of a well bore or the inside surfaces of casing cemented in the well bore. The gravel making up the gravel pack is often coated with a hardenable resin composition which is caused to harden whereby the sand is consolidated into a stationary permeable mass. Alternatively, the gravel packing operation may be performed as a high-rate water pack. In this instance, the carrier fluid comprises water or lightly gelled water injected at a high rate into the subterranean formation. Transport of the gravel contained in the fluid is achieved by the high fluid flow rate rather than through use of a gelling agent.
In all of the above described well treatments, the hardenable resin compositions utilized are caused to harden by formation heating or by contacting the resin with an internal or external hardening agent. While the particulate materials used have been successfully consolidated into stationary permeable masses, the hardening processes have taken time during which the wells have had to remain shut-in. The shut-in time required often exceeds a day. This shut-in time delays the start of production and therefore involves a considerable cost in the form of lost production. Thus, there is a need for improved methods of consolidating particulate material in wells whereby the consolidation process rapidly takes place.